Additives in packaged meat, poultry, and fish can contribute significantly to the dietary phosphorus and potassium loads in CKD patients, researchers say.

Phosphate additives are common in packaged meat, poultry, and fish (MPF) products, and the phosphorus content of food packages that list phosphate additives is higher than packages that do not, a Canadian study found.

In a study, Pauline B. Darling, PhD, RD, of the University of Ottawa, and collaborators asked 67 hemodialysis and peritoneal dialysis patients from Canada to complete a food frequency questionnaire. The top 8 MPF products consumed included unbreaded chicken, ground beef, steak, white fish, beef burgers, deli meats, bacon, and shrimp. MPF that did and did not list phosphorus and potassium additives on their ingredient label were separated into groups for analysis. Packaged foods do not always list additives, so the team used fresh MPF, completely free of additives and added ingredients, to serve as a control group.

Phosphorus, potassium, and sodium additives appeared on the ingredient list in 37%, 9%, and 72% of MPF, respectively. According to chemical analyses, phosphorus content was significantly higher in MPF listing phosphorus additives than in unlisted MPF and additive-free MPF: 270 vs 200 vs 210 mg per 100 g of food, respectively, on average.

Potassium additives had a similar effect. MPF listing a potassium additive had significantly more potassium than unlisted MPF and additive-free MPF: 900 vs 325 vs 420 mg per 100 g of food, respectively, on average. According to background information, potassium lactate is allowed in up to 4.8% of foods in the United States.

The findings, published online in the Journal of Renal Nutrition, agree with studies from the United States and Europe, the investigators stated. These additives potentially increase the risks for hyperphosphatemia and hyperkalemia.

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“The use of additives in packaged MPF products as indicated by the ingredient list can significantly contribute to the dietary phosphorus and potassium loads in patients with CKD,” Dr Darling and colleagues stated. “Patients with CKD should be educated to avoid MPF foods listing phosphorus and/or potassium additives on the ingredient list, which may lead to improved dietary adherence.”

In the United States, “enhanced products” typically contain phosphorus additives and should be avoided, the team stated. They also noted that even unlabeled seafood purchased from a grocery store counter can contain phosphate additives, introduced during thawing.